A portion of this patent disclosure involves material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
This invention relates in general to tracking of mobile items and, more particularly, to a method and apparatus which use radio frequency identification technology to track mobile items.
In an existing technique for tracking a mobile item, a device known as a tag is attached to the item, and communicates using radio frequencies signals with a central receiver known as a reader. While existing systems of this type have been generally adequate for their intended purposes, they have not been satisfactory in all respects.
In this regard, some existing tags can effect a transmission in response to an interrogation signal but, aside from this, pre-existing tags generally operate in a predetermined manner which is not subject to external influence. Further, interrogation signals of this type merely trigger a transmission by the tag, and do not effect a change in any operational characteristic of the tag. Thus, aside from replacing a given tag, there is no convenient way to easily change certain operational characteristics of the tag.
From the foregoing, it will be appreciated that a need has arisen for a method and apparatus for tracking items using radio frequency identification technology, in which it is possible to externally influence at least one operational characteristic of the tag. According to the present invention, a method and apparatus are provided to address this need, and involve: receiving in a receiver section of a tag wireless signpost signals that each include a signpost code and a command portion; transmitting from a transmitter section of the tag wireless beacon signals which each include a beacon code associated with the tag, the transmitter section being responsive to receipt by the receiver section of a respective signpost signal for including in at least one beacon signal the signpost code from the received signpost signal; and effecting a control function within the tag in response to the command portion of a respective signpost signal received by the tag